1. Field of the Invention
The present invention relates to spin coaters and methods of spin coating. More particularly the present invention is directed to recirculation spin coaters with minimal coating material loss and optical controls and methods of spin coating.
2. Background Information
Spin coating processes and associated spin coating machines are well known for efficiently providing a uniform coating to a substrate work piece. In particular lenses and wafers have used spin coating processes for the application of the completed lens and coating of wafers.
U.S. Published patent application serial number 20030079679 discloses a spin coater for dropping a chemical liquid onto a wafer W supported by the support table, whereas a front end part of the arm is provided with a nozzle for letting out the chemical liquid and the arm is horizontally rotatable by the driving motor.
U.S. Published patent application serial number 20020197400 discloses a spin-coater for coating a liquid material on a wafer that is equipped with a self-cleaning coating cup and a method for self-cleaning a spin-coater. The spin-coater is constructed of a coating cup of circular shape, a wafer pedestal situated in the cup, a coating material dispensing nozzle over the pedestal, a motor means for rotating the pedestal, and a solvent dispensing means that is mounted juxtaposed to an upper rim of the sidewall of the cup for dispensing a cleaning solvent onto an interior surface of the sidewall to dissolve and rinse off any liquid coating material splattered thereon and to prevent the formation of solid contamination from the solidified coating material.
U.S. Published patent application serial number 20020112662 discloses a waste fluid separation and recovery system for a spin coater including an exhaust airflow generator for generating an exhaust airflow.
U.S. Published patent application serial number 20070107657 discloses a device for spin-coating substrates. U.S. Published patent application serial number 20070076301 discloses a process for coloring an optical lens by spin coating which comprises (i) increasing or decreasing the temperature of at least one zone of the lens surface by at least 2° C. and (ii) simultaneously, or successively, depositing a colored coating comprising a volatile solvent over the entire surface of the lens by spin coating.
U.S. Published patent application serial number 20040072450 discloses methods and apparatuses useful for spin-coating process solutions onto substrates, wherein the methods and apparatuses incorporate a pressure sensor to detect the pressure of a process solution, such as a pressure related to a beginning or end of a dispense of process solution from a dispenser; some preferred methods and apparatuses measure pressure of a photoresist, developer, water, solvent, or cleaner in a dispense line; and some preferred methods and apparatuses incorporate process control systems involving interrupted, parallel control methods.
U.S. Published patent application serial number 20020108561 discloses an apparatus and methods for use in spin coating a coating material onto a wafer. The apparatus includes a rotatable chuck capable of supporting the wafer and a bowl having a bottom and a side defining an interior region, the bottom containing an opening through which the chuck is movable and separable from the bowl.
U.S. Pat. No. 6,352,747 discloses a spin and spray coating process for curved surfaces, particularly lenses. See also U.S. Pat. Nos. 6,326,054 and 6,129,042 disclosing a process and machine for coating optical lenses.
Methods for producing uniform coatings on substrates have been disclosed in numerous patents. U.S. Pat. No. 3,494,326 describes a spin-coating machine that includes a sealed compartment and means for providing a pressure differential in the area of the spinning lens. The controlled withdrawal and flow of air around the spinning lens due to the pressure differential reportedly enables providing a uniform coating on certain elongated lens shapes.
U.S. Pat. No. 5,094,884 describes an apparatus for applying a uniform layer of a fluid material on a substrate by using a dispensing nozzle having a rectangular or oblong shaped opening. The fluid material is dispensed while the nozzle moves along a radial path inwardly from the peripheral edge of the substrate.
U.S. Pat. No. 5,246,499 describes a coating system for applying a scratch-resistant coating to plastic ophthalmic lenses. The coating station of this system includes a coating arm assembly having nozzles which can be moved radially inwardly and outwardly over spinning lenses to apply the coating solution.
U.S. Pat. No. 5,514,214 describes an apparatus for and method of applying a UV curable monomer to the surface of an ophthalmic lens or mold. The substrate is sprayed with a UV curable solution while spinning at a high rate of speed to achieve a uniform coating. The coated substrate is then moved to a curing chamber to polymerize the monomer on the lens or mold.
U.S. Pat. No. 5,571,560 describes a method of coating a substrate that minimizes waste using a proximity dispenser that dispenses a liquid coating in the form of a stream from nozzles placed from 5 to 10 mm above the substrate.
U.S. Pat. No. 5,685,908 describes an apparatus for coating multifocal lens elements. The coating solution is applied using a nozzle that may be tilted while the lens is spun about an axis offset from the geometric center.
U.S. Pat. No. 5,766,354 describes a spin-coating device having the means to position the substrate at a predetermined angle while the fluid coating is dropped onto the rotating substrate.
Existing spin coaters do not effectively minimize coating material loss. Existing spin coaters do not effectively address work piece position for subsequent processing, which is particularly important for the manufacture of certain optical lenses. Existing spin coaters do not effectively address spin coater controls, particularly within a substantially closed spin coater environment. Existing spin coaters with a closed environment do not adequately address all coating materials. It is the objects of the present invention to generally improve spin coaters and methods of spin coating, to address the deficiencies of the prior art discussed above, and to do so in an efficient cost effective manner.